Measure 54 inches and tap the second nail next to the same joist (Image 1).
Snap a chalk line between the two nails (Image 2).
Using a carpenter’s square, line it up from the point of the nail and draw out 22-1/2 inches. Do this on both sides (Image 3).
Chalk a line between the two sides to complete the guidelines for the cut.
Place attic assembly on supports. Make sure you have someone helping from the garage level so you don’t get stuck in the attic.
Pull the stairs down until the hinges are extended (Image 1). Do not extend the legs to the floor yet.
Check that the assembly is level and shim between the stair frame and joists. After the shims are in place, drill the screws through the shims. It keeps them in place (Image 2).